The present invention relates to a valve, particularly, to a valve for regulating flow of a fluid therethrough. The valve according to the invention can keep flow of a fluid constant.
A fluid in a transfer system such as heat supply, air conditioning and water supply needs to be properly distributed in various branches of the system. The flow of the fluid in the branches relies on the pressure of the fluid in the system. In general, it is very difficult to control the flow of the branches in practice because the pressure of the fluid cannot be kept constant. As a result, a lot of energy has been lost.
A number of efforts have been made to overcome the drawbacks in the prior art. For example, people have provided various devices for keeping the flow of the fluid constant even if a pressure difference of the fluid of the transfer system occurs. Chinese utility model patent 96215731.7 (invented by the applicant of this PCT application) disclose a self-regulated balance valve which comprises a main valve body, an assistant part, a worm-drive butterfly clack, a double-seat clack (automatic valve core), and a pressure difference transducer consisting of a membrane, a spring and a membrane case. Although the valve disclosed in this patent may keep a constant flow in some range, the valve is of a complicated structure and a big volume because a fluid channel is needed to match the double-seat clack""s work. Moreover, the valve in question can only regulate the fluid with a small pressure change and cannot electrically or pneumatically be controlled.
Therefore, the object of the present invention is to provide a regulating valve for a constant flow, which has a simple and compact structure, a smaller size, a lower cost, a better property for keeping a constant flow of a fluid to overcome the shortcomings in the prior art. The flow of the fluid can be kept constant within a larger range of the pressure change suffered by the valve, if the flow is predetermined. The regulating valve according to the invention may be controlled not only manually, but also automatically by an electrical or a pneumatic actuator.
According to the present invention, there is provided a regulating valve comprising a valve body with a upper cover and a lower cover, having a upper chamber, a middle chamber and a lower chamber; and a valve stem, a sealing stuff, a sealing flange and an actuator being mounted to the center of the upper cover. A first clack positioned within the upper chamber and the middle chamber of the valve body is connected to the valve stem, the outer surface of the first clack is associated with the inner surface of the middle chamber of the valve body and faced to a throttle hole positioned on the inner surface of the middle chamber, the lower end of the valve stem is connected to one end of a pressure difference transducer, another end of the pressure difference transducer is connected to a second clack, which is associated with two concentric seats positioned between the middle chamber and the lower chamber of the valve body, a first channel is provided between the upper portion of an outlet chamber of the valve body and the upper chamber, and a second channel is provided between the upper chamber and the inside of the pressure difference transducer so that the outlet chamber is communicated with the inside of the pressure difference transducer.
The first clack in the invention may comprise a connecting sleeve at the upper portion thereof, to which the lower end of the stem is connected, and a sleeve at the lower portion, whose lower end is of an opening of an oblique plane. A sealing ring may be positioned in an O-flute at the outside of the connecting sleeve to attach the inner surface of the upper chamber. A hole is provided at the upper end of the sleeve in this invention.
The second clack used in the invention may be a cylinder whose upper end is closed, two circular projections are provided at the outside of the second clack, 3-6 guiding ribs perpendicular to the circular ribs are provided at the outside of the second clack to form 3-6 holes at the outside of the upper portion of the second clack, and on the upper end of the second clack is provided a square projection extended upwards through the square hole of the first clack.
In the regulating valve according to the invention, the pressure difference transducer is selected from those conventionally used in the art such as made of a bellows, a rubber membrane or a sliding piston.
The actuator used in the invention may be a manual, an electrical, or pneumatic one. The actuator is connected to a pointer fastened by a locking bolt. The pointer indicates the scale of a dial on the upper surface of the upper cover for showing the flow.
The regulating valve according to the invention further comprises a screw rod installed in the core of the valve stem. The lower end of the screw stem is connected to a cover for covering a spring connected to the bottom of the inner of the pressure difference transducer.
The regulating valve according to the invention will be described as follows.
First, the first clack is driven by rotating the valve stem via the actuator such as a handwheel. When the pointer on the handwheel rotates to a position where the scale shows the desired flow, the handwheel is locked by the locking bolt. In this case, the setting of the flow is completed. Thereafter, when the pressure of the fluid suffered by the regulating valve changes, the second clack is moved up and down together with the movement of the pressure difference transducer. This regulates the change of the flow caused by the pressure changes to keep the flow through the valve constant. Alternatively, an automatically regulating valve according to the present invention may be provided in an automatic control system, in which the valve is driven by an electrical or a pneumatic actuator instead of the handwheel. In this case, it may avoid the actuator of the valve being initiated frequently due to the pressure change, so as to improve the stability of the system and prolong the life of the valve.